Optical quickmount

ABSTRACT

A filter wheel assembly includes a filter wheel and an optical assembly. The filter wheel includes a plurality of viewing openings. The optical assembly includes an optical element secured within an aperture of a housing. The optical assembly is securable to the filter wheel at a viewing opening by a magnetic force. An optical apparatus includes an optical assembly receiver and first and second optical assemblies. The first optical assembly is securable to the optical assembly receiver and the second optical assembly is securable to the first optical assembly by a magnetic force to align the optical assembly receiver and the optical assemblies.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 13/734,748, filed on Jan. 24, 2013, the contents of which arehereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. The Field of the Invention

The present invention relates to quick release apparatuses and methods.Specifically, the present invention relates to quick release apparatusesand methods for installing and removing optical elements.

2. The Relevant Technology

High-content screening (“HCS”) is a cell-based screening method thatyields detailed information about the temporal-spatial dynamics of cellconstituents and processes, and plays an important role in the use ofcell-based screening for identification and validation of drugcandidates. The information provided by HCS alleviates bottlenecks inthe drug discovery process by providing deep biological information. Theassays associated with this method use either fixed or live cells,depending on the biological information desired.

In one method of performing an HCS scan, the cells of interest areloaded into an array of wells in a standard specimen plate (also knownas a titer or microtiter plate). The specimen plate is then positionedin a plate holder on a stage within an imaging system so that thespecimen plate can move horizontally with the stage. The imaging systemalso includes a microscope. Motors are attached to the stage so that thestage and the specimen plate can be moved with respect to the microscopein both directions orthogonal to the microscope. As a result, any of theindividual wells can be positioned in alignment with the microscope soas to be able to be imaged through the microscope objective.

The image obtained through the objective can be recorded using a camerasystem, such as, e.g., a Charge-Coupled Device (CCD) camera system. Awide variety of auxiliary components, such as electromechanical shuttersand axial focus control mechanisms can be used to aid in obtaining andrecording the images through the microscope. These components aretypically interactively controlled by a computer using proprietary orcommercially available image acquisition software.

Another useful component for automatic multi-color fluorescence imagingis a device for rapidly switching between different wavelengths oflight. In a conventional configuration, a fluorescence filter set ishoused in an optical block and contains an excitation filter and abarrier (or emission) filter, as well as a dichromatic mirror thatdirects excitation light to the specimen and transmits emission light toa detector in the camera system. For live-cell imaging using moreadvanced filter technology, the dichromatic mirror can be retained, butis often substituted for a polychromatic derivative that containsmultiple bandpass regions. The excitation and emission filters can beremoved from the optical block and placed in filter changers that caninclude a plurality of filter elements.

There are several practical mechanisms for automatically interchangingfluorescence filters. The most common involves rotating thin filterwheels having a number of filter elements mounted thereon. Filter wheelsare reliable, relatively inexpensive, and supported by a large number ofaftermarket and proprietary image acquisition programs. Among the majorbenefits of filter wheels are their high light transmission efficiencyand the flexibility to use a wide range of commercially availablefilters.

One of the disadvantages of filter wheels is their limitation inswitching speed. That is, it takes a finite amount of time to movebetween filter elements on the filter wheel. This can cause asignificant delay to build up when imaging many cells, as is often donein HCS scans. To help mitigate this limitation, conventional filterwheels are thin and light and only accommodate up to about ten filterelements at a time. Although this helps mitigate the speed issue, italso causes other problems. For example, filter wheels must be manuallychanged out every time a filter element is desired that is not mountedon the filter wheel being used. This takes significantly more time thanthe delay caused by moving between filter elements on the filter wheeland thus greatly exacerbates the speed delay problems. Because only afew filter elements are mounted on a filter wheel, the changing out offilters wheels can occur often, especially due to the nature offluoroscopy.

In some conventional configurations, the filter elements themselves arechanged out instead of the filter wheel. To accommodate this, eachfilter element can be part of a filter that is threaded into an apertureformed on the filter wheel. Conventional filters include housings,adapters and retaining rings. A lens or filter element is placed insidethe housing, which is usually circular, then held fast with an internalretaining ring. This sandwich of components, in turn, threads into theaperture on the filter wheel, often using an adapter to match thethreading on the aperture. Because of the thinness of the filter wheeland the filter assembly, the threads are very thin and precise. As aresult, a series of precise and costly threaded components are requiredon the filter components, along with special tools to change out thefilters. In addition, the small size of the threads requires a dexterityon the part of the user, and special care must be taken duringinstallation to not damage the components or the threads.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present invention will now be discussed withreference to the appended drawings. It is appreciated that thesedrawings depict only typical embodiments of the invention and aretherefore not to be considered limiting of its scope. In the drawings,like numerals designate like elements. Furthermore, multiple instancesof an element may each include separate letters appended to the elementnumber. For example two instances of a particular element “20” may belabeled as “20a” and “20b”. In that case, the element label may be usedwithout an appended letter (e.g., “20”) to generally refer to everyinstance of the element; while the element label will include anappended letter (e.g., “20a”) to refer to a specific instance of theelement.

FIG. 1 is a perspective view of an imaging system incorporating featuresof the present invention;

FIG. 2 is a perspective view of filter wheel station having an insetshowing detail of a filter wheel assembly positioned within the filterwheel station;

FIGS. 3A and 3B are perspective views of one embodiment of an opticalapparatus—a filter wheel assembly comprising a plurality of filtersmountable on a filter wheel, FIGS. 3A and 3B respectively showing thefilter wheel assembly before and after the plurality of filters havebeen mounted to the filter wheel;

FIG. 4 is a perspective view of one of the filters and a portion of thefilter wheel assembly of FIGS. 3A and 3B, showing how the filter ismounted to the filter wheel;

FIG. 5 is an exploded perspective view of one of the filters shown inFIGS. 3A and 3B;

FIGS. 6A-6C are cross sectional side views of alternative embodiments offilters;

FIGS. 7A-7D are cross sectional side views of a portion of a filtermounted onto a filter wheel showing alternative arrangements of magnetsand magnetic material;

FIG. 8A is a cross sectional side view showing one of the filtersmounted to the filter wheel, taken along the section line 8-8 of FIG.3B;

FIG. 8B is a cross sectional side view showing an alternative embodimentof a filter mounted to a filter wheel;

FIG. 9 is a cross sectional side view illustrating how a filter can bemounted to a filter wheel;

FIG. 10 is a cross sectional side view showing one embodiment of afilter wheel assembly in which a stack of filters are mounted on thefilter wheel;

FIG. 11 is a cross sectional side view of an alternative embodiment of afilter that can be stacked on a filter wheel;

FIGS. 12A and 12B are cross sectional side views of an alternativeembodiment of a stacked filter arrangement before and after mounting,respectively, on the filter wheel; and

FIG. 13 is a perspective view of another embodiment of an opticalapparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. The embodiments described in the detaileddescription, drawings, and claims are not meant to be limiting. Otherembodiments may be utilized, and other changes may be made, withoutdeparting from the spirit or scope of the subject matter presentedherein. It will be readily understood that the aspects of the presentdisclosure, as generally described herein, and illustrated in thefigures, can be arranged, substituted, combined, separated, and designedin a wide variety of different configurations, all of which areexplicitly contemplated herein. It will also be understood that anyreference to a first, second, etc. element in the claims or in thedetailed description, is not meant to imply numerical sequence, but ismeant to distinguish one element from another unless explicitly noted asimplying numerical sequence.

In addition, as used in the specification and appended claims,directional terms, such as “top,” “bottom,” “up,” “down,” “upper,”“lower,” “proximal,” “distal,” “horizontal,” “vertical,” and the likeare used herein solely to indicate relative directions and are nototherwise intended to limit the scope of the invention or claims.

The present invention relates to apparatuses and methods that allow forquick and easy installation and removal of optical elements in anoptical system. The apparatuses and methods are especially useful forfrequently changed components such as filters on a filter wheel.Embodiments of the invention allow the components to be changed withoutthe use of special tools (e.g., a spanner wrench), and eliminate theneed for costly threaded components, such as retaining rings and elementhousings.

Embodiments of the invention provide a fundamentally different way ofinstalling and removing optical elements. Instead of using physicalretaining rings, as is conventionally used in the art, embodiments ofthe present invention use a magnetic force in combination with a meansfor aligning the optical element with a viewing opening to quickly mountand secure the optical element to an optical assembly receiver withacceptable precision and repeatability. For each optical element, aportion of the means for aligning can be incorporated into a housing towhich the optical element is mounted to form an optical assembly. Theother portion of the means for aligning can be positioned on the opticalassembly receiver. The two portions of the means for aligning cancooperate with each other to quickly align the optical element of theoptical assembly with the viewing opening of the optical assemblyreceiver while the magnetic force secures the optical assembly to themounting location. For example, as discussed in more detail below, theoptical assembly can comprise a filter and the optical assembly receivercan comprise a filter wheel to which the filter is quickly mounted andaligned using portions of the means for aligning positioned on thefilter and the filter wheel.

To provide the magnetic force, one or more magnets can be positioned onor in the optical assembly or the optical assembly receiver or both. Inaddition or alternatively, the optical assembly and/or the opticalassembly receiver can be made of or incorporate a magnet. A “magnet” isdefined herein to be a material or object that produces a magneticfield, either permanent or electronically controlled. Furthermore, theoptical assembly and/or the optical assembly receiver can be made of orincorporate a magnetic material, which is defined herein to be amaterial that is attracted to a magnet due to the magnetic fieldproduced by the magnet.

Using the means for aligning and the one or more magnets to respectivelyalign and secure the optical element of the optical assembly to theoptical assembly receiver provides the precision necessary for mountingoptical elements, in line with geometric dimensioning and tolerancing(GD&T) fundamentals. As a result, instead of using conventional threadedoptical mounting assemblies, embodiments of the present inventioneliminate the need for threaded components in such systems and allow forquick installation and removal of optical assemblies in optical assemblyreceivers.

According to embodiments of the present invention, a user can performinstallation and removal of an optical assembly, such as a filter or alens, to and from an optical assembly receiver, such as a filter wheel,without the use of tools, if desired. In some embodiments, theinstallation and/or removal can be easy enough to be performed withoutviewing the installation and/or removal. As a result, quick installationand removal of the optical assembly to and from the optical assemblyreceiver can be accomplished. This can remedy the common annoyance ofslow installation and removal that plagues conventional opticalassemblies, such as, e.g., filters to and from filter wheels, and otheroptical devices. In addition, by eliminating conventional threadedcomponents, embodiments of the present invention generally cost less andare more resistant to damage that can occur with conventional productsduring installation and removal.

Once an optical assembly has been magnetically secured to the opticalassembly receiver, the loaded optical assembly receiver can be employedin a conventional manner to allow the loaded optical assembly to beselected and positioned in the viewing path of a user or device of anoptical system as desired, to manipulate the view. One example of such asystem is an imaging system that uses filters or other opticalassemblies to perform the imaging of one or more objects.

For example, depicted in FIG. 1 is an imaging system 100 that canincorporate features of the present invention. Imaging system 100 can beused to scan and analyze biological cells, as is known in the art. Insome embodiments, imaging system 100 can be used for high contentscreening, as is also known in the art. Imaging system 100 is shown inFIG. 1 in a generalized live-cell imaging configuration.

Imaging system 100 comprises a stage assembly 102 mounted on amicroscope assembly 104. Stage assembly 102 includes a stage 105 onwhich a slide or well plate can be positioned for viewing, as is knownin the art. As shown in FIG. 1, stage assembly 102 can also include anenvironmental control chamber 106, if desired. Microscope assembly 104houses an inverted microscope 108 that can be used to perform screeningof specimens on the slide or well plate from underneath the specimens.Microscope 108 includes one or more objectives, as are known in the art,to obtain magnified views of the specimens.

Imaging system 100 can also include an image capture assembly 110optically coupled to microscope 108 to record the image of the specimensobtained through the objective. Image capture assembly 110 can comprisea camera system 112 (e.g., a CCD camera system), an excitation filterassembly (not shown), an emission filter assembly 114, and one or morelight tubes 116 that direct the emission light from the objective,through emission filter assembly 114 and to camera system 112, as isknown in the art.

FIG. 2 shows an exemplary filter assembly 114 that can be used as anexcitation filter assembly or an emission filter assembly. Filterassembly 114 can comprise a housing 120 to which a filter wheel assembly122 is mounted. Filter wheel assembly 122 can be an excitation filterwheel assembly or an emission filter wheel assembly, depending on howfilter assembly 122 is going to be used. Filter assembly 114 can includea motor (not shown) for rotating filter wheel assembly 122 as well ashardware 123, e.g., fasteners, shafts, etc. for mounting the motor andfilter wheel assembly 120 to housing 120 such that filter wheel assembly122 can be rotated by the motor, in some embodiments under the directionof a controller, as is known in the art.

FIGS. 3A and 3B depict one embodiment of a filter wheel assembly 122according to the present invention. Filter wheel assembly 122 comprisesa filter wheel 124 to which a plurality of filters 126 (126 a-d) aremagnetically mountable. FIGS. 3A and 3B respectively show filter wheelassembly 122 before and after filters 126 have been mounted or securedto filter wheel 124. As shown in FIG. 3B, filters 126 can be secured tofilter wheel 124 concurrently.

Filter wheel 124 corresponds to an optical assembly receiver of thepresent invention and comprises a main body 128 having a first face 130and an opposing second face 132 with a perimeter sidewall 134 extendingtherebetween. Filter wheel 124 is generally circular, although this isnot required. Filter wheel 124 has a central rotational axis 136 thatpasses through main body 128 and is generally orthogonal to first andsecond faces 130, 132; it is about this central rotational axis 136 thatfilter wheel 124 is rotated during use by the motor within filter wheelstation 120. Filter wheel 124 is generally thin to allow for quickrotation about central rotational axis 136. Filter wheel 124 can be anydiameter (if circular) or any other size commonly used in the art. Forexample, filter wheel 124 can have a diameter of between about 5 cm toabout 25 cm, with about 10 cm to about 20 cm being common. Of courseother diameters are also possible.

Filter wheel 124 can be comprised of any material to which filters 126can be releasably mounted and that can withstand the forces placed onfilter wheel 124 by rotation about central rotational axis 136 caused bythe motor. To allow each filter 126 to be magnetically secured thereto,filter wheel 124 can include one or more magnets positioned thereon ortherein, as discussed in more detail below. Alternatively or inaddition, filter wheel 124 can be comprised of a magnetic material, suchas a ferrous metal.

Main body 128 includes one or more mounting holes 138 formed thereon toaid in mounting filter wheel 124 to filter wheel station 120. Mountingholes 138 can be used to receive a shaft of the motor as well as othercontrolling devices, as is known in the art.

A plurality of viewing openings 140 (140 a-d) are also formed in mainbody 128 so as to extend therethrough. As shown in FIG. 4, each viewingopening 140 is bounded by an inner sidewall 142 extending between firstand second faces 130, 132 of main body 128. Viewing opening 140 isgenerally circular about a central axis 144 substantially parallel torotational axis 136. Viewing opening 140 can have a size commonly usedin the art. For example, viewing opening 140 can have a diameter ofbetween about 1 cm to about 8 cm, with about 2 cm to about 5 cm beingcommon. Other shapes and sizes are also possible.

As shown in FIG. 3A, viewing openings 140 are positioned on filter wheel124 so as to be radially spaced about central rotational axis 136. As aresult, as filter wheel 124 is rotated about central rotational axis136, each viewing opening 140, in turn, can be rotated to a positionthat aligns the viewing opening 140 with the imaging path, as is knownin the art, to use the filter 126 mounted at the corresponding viewingopening 140.

Any number of viewing openings 140 can be formed on the filter wheel124. In the depicted embodiment, four viewing openings 140 a-d areformed on filter wheel 124. In other embodiments, more or less viewingopenings 140 can be formed. For example, the number of viewing openings140 on filter wheel 124 can range from two to sixteen with four to eightbeing common. Of course, other numbers of viewing openings 140 can alsobe used.

As shown in FIGS. 3A and 3B, filter wheel 124 can have a separate filter126 mounted thereto at each viewing opening 140. As noted above, filter126 corresponds to an optical assembly of the present invention. Turningto FIG. 5 in conjunction with FIG. 4, each filter 126 comprises ahousing 150 shaped and sized so as to be positionable at any of viewingopenings 140 of filter wheel 124. As such, housing 150 is generallyring-shaped, having a first side surface 152 and an opposing second sidesurface 154 with an outer perimeter wall 156 and an inner perimeter wall158 extending between the opposing side surfaces 152, 154.

Inner perimeter wall 158 bounds an aperture 160 that is generallycircular about a central axis 162 substantially orthogonal to first andsecond side surfaces 152 and 154. Aperture 160 is sized to beapproximately the same size as viewing opening 140, but may be larger orsmaller than viewing opening 140. As such, the same ranges of sizesdiscussed above with respect to viewing opening 140 can also generallyapply to aperture 160. In one embodiment, the diameter of aperture 160is substantially the same as the diameter of viewing opening 140.

Housing 150 is generally sized and shaped to overlap viewing opening 140so that housing 150 can mount to the portion of main body 128 thatencircles viewing opening 140. As such, the outer perimeter of housing150 can also be generally circular about central axis 162, with thediameter of outer perimeter wall 156 being greater than the diameter ofviewing opening 140. Although housing 150 and aperture 160 are discussedas being generally circular, other shapes are also possible, as long asaperture 160 can be aligned with viewing opening 140 while housing 150overlaps viewing opening 140 to be mounted to main body 128 of filterwheel 124.

As shown in FIG. 5, filter 126 further includes an optical element 170secured to housing 150 so as to cover or be positioned within aperture160. Optical element 170 has a first face 172 and an opposing secondface 174 with a perimeter sidewall 176 extending therebetween at aperimeter portion 178 of optical element 170. Optical element 170 isgenerally sized and shaped to fully cover or fill aperture 160. As such,optical element 170 can have a diameter that is slightly larger than thediameter of aperture 160. Optical element 170 can be made of glass,plastic, or other optical material now known in the art or envisioned inthe future. Optical element 170 can comprise a filtering component orother optical component. Some examples include: relay or magnificationlenses, bandpass, edgepass and notch filters, neutral density filters,dichroics, beamsplitters, diffraction gratings, apertures, diffusers.

Optical element 170 is typically permanently secured to housing 150,although optical element 170 can alternatively be removable, if desired.Optical element 170 can be secured to housing 150 in a number ofdifferent ways. In one embodiment, optical element 170 is attached tohousing 150 using adhesive or welding techniques known in the art. Forexample, first face 172 of optical element 170 can be adhered to secondside surface 154 of housing 150, as shown in the depicted embodiment.Alternatively, second face 174 of optical element 170 can be adhered tofirst side surface 152 of housing 150. In those embodiments, outerperimeter portion 178 (the portion of optical element 170 radiallyoutside of dashed line 180) overlaps housing 150 so as to be adhered tohousing 150. Alternatively, outer perimeter 178 of optical element 170can be secured to housing 150 using fasteners, such as set screws or thelike. Other attachment techniques may also be used, as is known in theart.

FIGS. 6A-6C show alternative manners of securing optical element 170 tohousing 150. In FIG. 6A, an annular groove 182 is formed on one of theside surfaces (second side surface 154 in the depicted embodiment) ofhousing 150. Groove 182 is formed where side surface 154 intersectsinner perimeter wall 158 so as to encircle aperture 160. Outer perimeterportion 178 of optical element 170 is secured within annular groove 182.In FIG. 6B, an annular channel 184 is formed on inner perimeter wall 158of housing 150 between side surfaces 152 and 154. Optical element 170 ispositioned within aperture 160 so that outer perimeter portion 178 ofoptical element 170 is positioned within annular channel 184 and securedtherein. In FIG. 6C, housing 150 is comprised of two halves 186 a and186 b that are adhered or otherwise secured together to form housing150. Optical element 170 can be positioned between halves 186 a and 186b before assembly of housing 150 so that optical element 170 is securedwithin housing 150 when halves 186 a and 186 b are brought together, asdenoted by arrows 188, to form housing 150. If desired, an annulargroove can be formed in each half 186 so that when halves 186 arebrought together, the grooves together form an annular channel, similarto channel 184 of FIG. 6B in which optical element 170 is positioned.Other manners of securing optical element 170 to housing 150 are alsopossible.

As noted above, the optical assemblies can be magnetically secured tothe optical assembly receiver. To do so, one or more magnets can be usedto produce the magnetic field required to generate the magnetic forcenecessary to secure the optical assembly to the optical assemblyreceiver. For example, returning to FIG. 5, as an optical assembly,filter 126 can include a magnet 200 secured to housing 150 or formedtherewith.

Magnet 200 can be adhered or attached to first or second side surface152, 154. Alternatively, a mounting hole 202 can be formed on housing150 to receive magnet 200, as in the depicted embodiment. Mounting hole202 can be formed on first side surface 152 or second side surface 154or can extend all the way through housing 150 between the two surfaces.Magnet 200 can be friction fit within mounting hole 202, be adheredtherein, or a combination of both. Alternatively, magnet 200 andmounting hole 202 can be threaded so that magnet 200 can be screwed intomounting hole 202. In some embodiments, one or more fasteners, such as,e.g., set screws or the like, can be used to secure magnet 200 withinmounting hole 202. Other methods of mounting and securing magnet 200 canalso be used.

In one embodiment, magnet 200 can be incorporated into housing 150 so asto be substantially flush with either of side surfaces 152, 154 (see,e.g., FIG. 6A) or completely embedded within housing 150 (see, e.g.,FIG. 6B).

For a magnetic force to be generated that is sufficient to secure theoptical assembly to the optical assembly receiver, all or portions ofthe optical assembly receiver can be comprised of or incorporate amagnetic material that is attracted to the magnet. For example, asdiscussed above, main body 128 of filter wheel 124 can be comprised of ametal or other magnetic material 203 that is attracted to magnet 200, asdepicted in FIG. 7A. Alternatively, the optical assembly receiver can bemade of a non-magnetic material but can incorporate magnetic material inportions thereof. For example, FIG. 7B shows an embodiment in which aninsert 204 comprised of magnetic material is used in filter wheel 124.Inserts 204 can be positioned within filter wheel 124 so as to generallyalign with magnets 200 when filters 126 are secured to filter wheel 124.

Alternatively, or in combination, the optical assembly receiver canincorporate one or more magnets. For example, FIG. 7C shows anembodiment in which a magnet 206 is incorporated into filter wheel 124instead of into filter 126. In this embodiment, all or portions ofhousing 150 can be comprised of or incorporate magnetic material 203that is attracted to magnet 206. Magnet 206 can be attached to orincorporated into filter wheel 124 in a similar manner discussed abovewith respect to magnet 200 of housing 150.

FIG. 7D shows an embodiment in which housing 150 and filter wheel 124respectively include magnets 200 and 206. For maximum affect, magnets200 and 206 can be located so as to be aligned (i.e., opposing eachother) when filter 126 is mounted onto filter wheel 124. Using opposingmagnets on filter 126 and filter wheel 124 can enhance the magneticforce therebetween, thereby allowing smaller magnets to be used togenerate the same magnetic force as when only using a single magnet.When opposing magnets 200 and 206 are used, the poles of magnets 200 and206 that face each other should be oppositely charged to attract eachother. Otherwise, magnets 200 and 206 will repel each other, therebypreventing filter 126 from becoming secured to filter wheel 124.

In an alternative embodiment, either one of the housing and the filterwheel can be entirely or substantially, i.e., more than 50%, made of amagnet material and the other one can be comprised of a magneticmaterial attracted to the magnet material. Alternatively, both thehousing and the filter wheel can be entirely or substantially made of amagnet material. If enough magnet material is used to make the housingand/or the filter wheel, a separate magnet may not be needed; the magnetmaterial may provide the magnetic field necessary to produce themagnetic force to secure the filter to the filter wheel.

Magnets 200 can be of any practical size and shape to provide themagnetic force required to secure the optical assembly to the opticalassembly receiver. In one embodiment, each magnet 200 is circular andhas a diameter in a range of between about 3 mm to about 20 mm, withabout 6 mm to about 12 mm being common. In some embodiments, each magnet200 has a diameter that is less than 20 mm. Other diameters are alsopossible. In some embodiments, one or more magnets 200 are square,rectangular, oval, or any other regular or irregular shape. Thethickness of magnets 200 can also depend on the magnetic force required.In one embodiment, the thickness of each magnet 200 is less than orequal to the thickness of filter wheel 124. Other thicknesses are alsopossible. Magnets 200 can be made of any magnet material, such asneodymium, alnico or ferrite. Other materials can also be used formagnets 200.

The magnetic pull force F_(p) required to secure the optical assembly tothe optical assembly receiver can vary, depending on the size, shape,weight, and composition of the optical assembly, as well as otherfactors. The magnetic force is also directly dependent on the magneticfield B of magnet 200. In one embodiment, F_(p) of magnet 200 rangesbetween about 1 N and about 35 N with about 10 N and about 20 N beingcommon. Other values of F_(p) are also possible.

Most of the discussion and examples above are directed to the use of asingle magnet (e.g., magnet 200) on the optical assembly, a singlemagnet (e.g., magnet 206) on the optical assembly receiver, or acorresponding magnet pair on the optical assembly and the opticalassembly receiver. However, it should be appreciated that a plurality ofmagnet and/or magnet pairs can also be used. For example, two, three,four, or more magnets and/or magnet pairs can be used on filter 126and/or filter wheel 124, if desired. Each of the magnet and/or magnetpairs can be spaced around the perimeter of housing 150 and/or theportion of main body 128 that encircles viewing opening 140. Inaddition, each of the magnets can be secured to housing 150 or filterwheel 124 in a same manner as each other or can be secured differentlyfrom each other. For example, a magnet can be embedded within housing150 and another magnet attached to an outer surface thereof, if desired.Of course, other magnet arrangements can also be used.

As noted above, means can be used for aligning the optical element ofthe optical assembly with a viewing opening of the optical assemblyreceiver. These means can be used in conjunction with the magnetic forceto quickly mount and secure optical elements to an optical assemblyreceiver. Also as noted above, portions of the means for aligning can beincorporated into the housing to which the optical element is mounted aswell as the optical assembly receiver. As discussed above, in someembodiments, such as filter wheel assembly 122, the optical assembly cancomprise a filter, and the optical assembly receiver can comprise afilter wheel. As such, in those embodiments, the means for aligning theoptical element of the optical assembly with a viewing opening of theoptical assembly receiver is synonymous with means for aligning theoptical element of the filter with a viewing opening of the filterwheel, and portions of the means for aligning can be incorporated on thefilter and the filter wheel

In filter wheel assembly 122, the means for aligning the optical elementof the optical assembly with a viewing opening of the optical assemblyreceiver can comprise a plurality of first coupling portions positionedadjacent one of the viewing openings 140 of main body 128 and aplurality of second coupling portions positioned on housing 150 that arecomplementary to the first coupling portions so that when the opticalassembly (i.e., filter 126) is secured to the optical assembly receiver(i.e., filter wheel 124), the second coupling portions couple with thefirst coupling portions.

In one embodiment, the means for aligning can comprise mating pairs oftenons and mortises positioned on the optical assembly and the opticalassembly receiver. For example, as shown in FIG. 4, filter 126 caninclude two mating pairs 208 (208 a-b) that each comprise a pin 210 (210a-b) formed in or attached to housing 150 that can be snugly receivedwithin a corresponding hole 212 (212 a-b) formed in main body 128 offilter wheel 124 about each viewing opening 140. As such, mating pair208 a comprises pin 210 a and corresponding hole 212 a and mating pair208 b comprises pin 210 b and corresponding hole 212 b. As shown in FIG.8A, pin 210 is a tenon and hole 212 is a mating mortise when filter 126is aligned and mounted to filter wheel 124. Holes 212 can extendcompletely through housing 150 or a portion thereof.

The mating tenon/mortise pairs can be positioned so that the centralaxis of the viewing opening is aligned or collinear with the centralaxis of the aperture when the optical assembly is mounted to the opticalassembly receiver. This ensures that the optical element and the viewingopening are aligned when the optical assembly is mounted to the opticalassembly receiver. For example, in the embodiment shown in FIG. 8A, asfilter 126 is mounted to filter wheel 124, pins 210 are received withinholes 212 such that central axis 162 of aperture 160 becomes alignedwith central axis 144 of viewing opening 140. This ensures that opticalelement 170 and viewing opening 140 are aligned.

Besides aligning optical element 170 with viewing opening 140,tenon/mortise pairs 208 can also prevent optical element 170 frombecoming unaligned with viewing opening 140. When two or more pins 210are received within their corresponding holes 212, filter 126 cannotrotate or otherwise move with respect to filter wheel 124. In contrast,if only one tenon/mortise pair 208 was used, filter 126 might be able torotate with respect to filter wheel 124 using the single tenon/mortisepair as a pivot point. If this were to occur, optical element 170 wouldbecome unaligned with viewing opening 140. Thus, using only a singletenon/mortise pair 208 is generally not desired. However, if the shapeof the tenon/mortis pair is not radially symmetrical, such as, e.g.,elliptical, square, rectangular, or irregular, the shape may prevent thefilter assembly from rotating and a single tenon/mortise pair may beenough to prevent rotation.

In one embodiment, however, the magnet can be used as a tenon with acorresponding recess positioned to receive the magnet used as a mortise(see, e.g., magnets 200 and recesses 264 of FIG. 10). In that case asingle pin/hole combination 208 can be used with the magnet/recesscombination to provide two tenon/mortise pairs, which can allow forcorrect rigid alignment of the optical element with respect to theviewing opening. More than two tenon/mortise pairs can also be used ifdesired, although this is not necessary.

Although the discussion above relates to tenons on the optical assemblyand corresponding mortises on the optical assembly receiver, it isappreciated that the opposite is also possible. That is, tenons can bepositioned on the optical assembly receiver and mortises can bepositioned on the optical assembly. For example, FIG. 8B depicts analternative embodiment of a filter 220 having holes 222 formed thereininstead of pins. Accordingly, main body 128 of filter wheel 124 has pins224 attached to or formed thereon that can mate with holes 222.

It is appreciated that other types of means for aligning besides tenonsand mortises can also be used. For example one or more fasteners, suchas clips, screws, or other type of fasteners can be used as a means foraligning the optical element with the viewing opening. Alternatively,the means for aligning can comprise one or more channels and matingflanges positioned on the optical assembly, e.g., filter, and theoptical assembly receiver, e.g., filter wheel. Other types of means foraligning can also be used.

An optical assembly can be mounted and removed from an optical assemblyreceiver with relative ease by simply aligning the tenon/mortise pairsand pushing the optical assembly onto the optical assembly receiver. Anexemplary method of mounting and securing an optical assembly to anoptical assembly receiver will now be set forth with reference to FIG.9.

The first step of the method comprises aligning an aperture of theoptical assembly with a viewing opening of the optical assembly receiverso as to align first coupling portions on the optical assembly withmating second coupling portions on the optical assembly receiver.

Referring to FIG. 9, this step can be performed by positioning filter126 (an optical assembly) over one of the viewing openings 140 of filterwheel 124 (an optical assembly receiver) and rotating filter 126, ifnecessary, until mating pins 210 and holes 212 (first and secondcoupling portions) become aligned. Using lead-in chamfers in pins 210and/or holes 212 will help guide the filter assembly onto the filterwheel.

The second step of the method comprises while the first and secondcoupling portions are aligned, moving the optical assembly closer to theoptical assembly receiver until the first coupling portions couple withthe second coupling portions and a magnetic force secures the opticalassembly to the optical assembly receiver.

Again referring to FIG. 9, this step can be performed by moving filter126 toward filter wheel 124, as indicated by arrows 250, until pins 210are received within mating holes 212 and the magnetic force betweenmagnet 200 and the magnetic material causes filter 126 to be secured tofilter wheel 124.

Because of the ease by which the method can be done, the mounting andsecuring of the optical assembly to the optical assembly receiver may beaccomplished quickly and easily without the use of any tools. Of course,the above method can be adapted based on the means for aligning that isused.

If the optical assembly receiver is designed to have more than oneoptical assembly concurrently secured thereto, the steps discussed abovecan be repeated to mount the rest of the optical assemblies to theoptical assembly receiver. For example, multiple filters 126 can beconcurrently mounted and secured to filter wheel 124 by repeating thesteps discussed above for each filter 126.

Removing or dismounting an optical assembly from an optical assemblyreceiver can also be performed with relative ease. The optical assemblycan be manually grasped and pulled away from the optical assemblyreceiver to overcome the magnetic force securing the optical assembly tothe optical assembly receiver.

For example, referring to FIG. 9, filter 126 can be manually grasped andpulled away (i.e., in the opposite direction as arrows 250) from filterwheel 124 with sufficient force to overcome the magnetic force securingfilter 126 to filter wheel 124. Once the magnetic force is overcome,filter 126 moves away from filter wheel 124, causing pins 210 to exitholes 212 so that filter 126 disengages from filter wheel 124. Similarto the mounting and securing method discussed above, removing ordismounting filter 126 may be accomplished quickly and easily withoutany tools due to the ease by which the removal is accomplished.

In some embodiments, optical assemblies can be stacked on the opticalassembly receiver so the light can pass through all of the stackedoptical assemblies. For example, FIG. 10 depicts an embodiment in whichthree filters (126 a, 126 b, and 220) can be stacked on filter wheel 124so that central axes 162 of all of the filters align. As such, when thestacked filters are secured to filter wheel 124, central axes 162 of thefilters and central axis 144 of filter wheel 124 can be collinear.

To allow each optical assembly to be mounted to an adjacent opticalassembly in the stack, means for aligning the apertures of adjacentoptical assemblies can be used. These means can be used in conjunctionwith the magnetic force forces on one or both of the adjacent opticalassemblies to quickly mount and secure the adjacent optical assembliesto each other. Portions of the means for aligning the apertures ofadjacent optical assemblies can be incorporated into each of thehousings of the adjacent optical assemblies.

In one embodiment, the means for aligning the apertures of adjacentoptical assemblies can comprise a plurality of first coupling portionspositioned on one of the housings and a plurality of second couplingportions positioned on the other housing that are complementary to thefirst coupling portions so that when the optical assemblies are securedtogether, the second coupling portions couple with the first couplingportions.

Similar to the means for aligning the optical element with a viewingopening of the optical assembly receiver, discussed above, the first andsecond coupling portions can comprise mating tenon/mortise pairs, suchas matching pins and holes.

For example, as shown in FIG. 10, adjacent filters 126 a and 220 includea pin 260 and matching hole 220. Pin 260 and hole 222 are respectivelypositioned on the sides of filter 126 a and filter 220 that face eachother. As such, hole 222 can receive pin 260 when filters 126 a and 220are brought together and secured by the magnetic force of the filters.

If desired, both sides of the optical assembly can include portions ofmeans for aligning adjacent optical assemblies such that the portions oneach side of the optical assembly can be used to align with a differentadjacent optical assembly. For example, hole 222 extends all the waythrough filter 220 so that hole 222 can be used as a mortise on bothsides of filter 220. As such, hole 222 can be used as a portion of themeans for aligning the apertures of adjacent optical assemblies(filters) 126 a and 220 as well as a portion of the means for aligningthe apertures of adjacent optical assemblies (filters) 220 and 126 b.Similarly, filter 126 b has pins 210 and 260 on opposite sides thereof;pins 210 can align with holes 222 of filter 220, while pins 260 canalign with another filter on the opposite side of filter 126 b. Bycontinuing to add optical assemblies in this manner, any number ofoptical assemblies can be stacked up. The first optical assembly in thestack can be secured to the optical assembly receiver as discussedabove, either before or after one or more other optical assemblies havebeen stacked onto the first optical assembly.

The mating tenon/mortise pairs of each optical assembly can bepositioned so that the central axes of the apertures of the adjacentoptical assemblies are aligned or collinear with each other when theadjacent optical assemblies are secured together. This can ensure thatthe optical elements are aligned when the optical assemblies are securedto the optical assembly receiver.

In one embodiment, two types of optical assemblies can be used in thestack. For example, as shown in FIG. 10 and discussed above, filters 126a and 126 b each have pins 210 and 260 extending from opposing sidesthereof, while filter 220 has a mating hole 220 extending completelytherethrough. As such, a filter stack can be built by simply alternatingthe different types of filters 126 and 220, as shown in FIG. 10.Although the depicted embodiment only shows three stacked filters, anynumber of filters can be stacked using this alternating filter approach,although practical considerations may limit the number of filters in thestack.

Alternatively, a single type of optical assembly can be used in thestack, if desired. For example, a first optical assembly can have atenon on one side surface and a mortise on the opposite side surface sothat an optical assembly having the same configuration can be alignedwith and secured to the first optical assembly. For example, FIG. 11depicts an embodiment of a filter 270 having pins 272 extending from oneside surface and holes 274 formed in the opposite side surface. Pins 272can be formed with or attached to housing 150 so as to align with holes274. As a result, filters 270 can be stacked up with pins 272 of onefilter 270 being received within holes 274 of an adjacent filter. Thus,the same type of filter can be used for each layer of the stack.

The means for aligning the apertures of adjacent optical assemblies cantake many forms. The discussion of the various embodiments of the meansfor aligning the optical element with the viewing opening, discussedabove, can also apply to the means for aligning the apertures ofadjacent optical assemblies.

Adjacent optical assemblies can be mounted and secured to each other ina similar manner to that described above with respect to the mountingand securing of optical assemblies to the optical assembly receiver. Anexemplary method of mounting and securing a pair of adjacent opticalassemblies to each other will now be set forth with reference to FIG.10.

The first step of the method comprises aligning the apertures of theadjacent optical assemblies so as to align mating coupling portions onthe facing surfaces of the optical assemblies with each other.

Referring to FIG. 10, this step can be performed by positioning filter220 adjacent filter 126 a and rotating filter 220 with respect to filter126 a, if necessary, until mating pins 260 and holes 222 become aligned.

The second step of the method comprises while the first and secondcoupling portions are aligned, moving the optical assemblies closer toeach other until the first coupling portions couple with the secondcoupling portions and a magnetic force secures the optical assembly tothe optical assembly receiver. The magnetic force can originate witheither or both of the optical assemblies. If desired, one or morerecesses (e.g., recess 264) can be formed on one or both of the filtersto accommodate magnets or any other projection extending from anadjacent filter.

Again referring to FIG. 10, this step can be performed by moving filter220 closer toward filter wheel 126 a, as indicated by arrows 266, untilpins 260 are received within mating holes 222 and the magnetic forcebetween magnets 200 on both filters causes filter 220 to be secured tofilter 126 a.

The above method can be performed for each optical assembly added to thestack.

To mount and secure the stacked optical assemblies to the opticalassembly receiver, the first optical assembly in the stack can bemounted and secured to the optical assembly receiver using the methoddiscussed above. The first optical assembly can be mounted and securedto the optical assembly receiver before or after other opticalassemblies are mounted on the first optical assembly to form the stack.

The first step of the method comprises aligning an aperture of theoptical assembly with a viewing opening of the optical assembly receiverso as to align first coupling portions on the optical assembly withmating second coupling portions on the optical assembly receiver.

In an alternative stacking embodiment, a portion of the means foraligning the apertures of the adjacent optical assemblies can bepositioned on the optical assembly receiver. In one embodiment, tenonsthat are substantially longer than the width of each optical assemblycan be positioned on the optical assembly receiver and correspondingmortises can extend completely through one or more optical assemblies sothat each tenon can be received within more than one of the mortises ofthe stacked optical assemblies.

For example, FIGS. 12A and 12B depict an alternative embodiment of afilter wheel 280 that includes pins 282 formed on or attached to mainbody 128 that are substantially longer than the width of each filter220. Because holes 222 of filters 220 extend completely through housing150, pins 282 can extend completely through holes 222. Furthermore,because pins 282 are substantially longer than the width of each filter,filters 220 can be stacked so that pins 282 extend through aligned holes222 of each filter 220 when filters 220 are mounted to filter wheel 280,as shown in FIG. 12B. The magnetic force of each filter 220 securesfilters 220 to each other and to filter wheel 280. The number of filters220 that can be stacked in this arrangement is limited by the length ofpins 282.

Because a portion of the means for aligning the apertures of theadjacent optical assemblies can be positioned on the optical assemblyreceiver, the means for aligning the optical element of the opticalassembly with a viewing opening of the optical assembly receiver and themeans for aligning the apertures of adjacent optical assemblies can becombined to form a means for aligning apertures of adjacent opticalassemblies with a viewing opening of the optical assembly receiver.

For example, the means for aligning apertures of adjacent opticalassemblies with a viewing opening of the optical assembly receiver cancomprise a plurality of tenons projecting from the main body of theoptical assembly receiver, a plurality of mortises extending completelythrough a housing of a first optical assembly; and a plurality ofmortises formed on a housing of a second optical assembly, such thatwhen the first optical assembly, the second optical assembly, and thereceiver are secured together, each of the tenons extends through one ofthe mortises of the first housing and into one of the mortises of thesecond housing.

Although the embodiments discussed above have been directed mostly tofilters and filter wheels, respectively, as the optical assemblies andoptical assembly receivers of the present invention, embodiments of thepresent invention can also be directed to other types of opticalassemblies and optical assembly receivers.

For example, FIG. 13 shows an alternative embodiment of an opticalapparatus 230 in which the optical assembly receiver comprises a cageback plate 232 and the optical assembly comprises a cage front plate 234used in an optical cage. The general concept of optical cages is knownin the art and will therefore not be discussed herein, except to saythat the optical cage is used to align optical devices. Cage back plate232 is similar to filter wheel 124 except that cage back plate 232 onlyhas a single viewing opening 236 formed therethrough and is mountedwithin a cage using a plurality of rails 238. As such, cage back plate232 does not rotate. Cage front plate 234 is similar to filter 126,except that optical element 170 positioned within aperture 160 istypically a lens or other type of optical element. Any of the methodsdiscussed above can be applied to optical apparatus 230, adapting themethods where necessary based on the apparatus. For example, cage frontplate 234 can be mounted to cage back plate 232 in any of the mannersdiscussed above and secured thereto by a magnetic force. Furthermore,cage front plates 234 can be stacked on cage back plate 232 in a similarmanner to that discussed above.

In addition, mirrors, achromatic doublets and triplet lens assemblies,prisms, fiber optic assemblies, objectives, and polychroic cubehousings.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. Accordingly, thedescribed embodiments are to be considered in all respects only asillustrative and not restrictive. The scope of the invention is,therefore, indicated by the appended claims rather than by the foregoingdescription. All changes which come within the meaning and range ofequivalency of the claims are to be embraced within their scope.

What is claimed is:
 1. A filter wheel assembly comprising: a filter wheel comprising a main body bounding a plurality of viewing openings extending therethrough, a first magnet being positioned in or on the main body; and a first optical assembly comprising: a first housing bounding an aperture extending therethrough; and a first optical element secured to the first housing so as to be positioned within or aligned with the aperture, the first optical assembly being removably secured to the filter wheel at a first one of the viewing openings by a first magnetic force between the first optical assembly and the filter wheel, the first magnetic force being caused by the first magnet.
 2. The filter wheel assembly recited in claim 1, further comprising a second magnet positioned in or on the first housing so as to be aligned with the first magnet to add to the magnetic force.
 3. The filter wheel assembly recited in claim 1, wherein the aperture of the first optical assembly is aligned with the first viewing opening.
 4. The filter wheel assembly recited in claim 1, further comprising a second optical assembly removably secured to the filter wheel at a second one of the viewing openings by a second magnetic force between the second optical assembly and the filter wheel.
 5. The filter wheel assembly recited in claim 4, wherein the second optical assembly has a second optical element secured to a second housing, the second optical element being aligned with the second viewing opening.
 6. An imaging system comprising: a microscope assembly comprising one or more objectives; a stage assembly mounted on the microscope assembly; and a filter wheel assembly as recited in claim 1 optically coupled with the microscope assembly.
 7. The optical apparatus recited in claim 1, wherein the first optical element is an optical lens.
 8. The optical apparatus recited in claim 1, wherein the first optical element is an optical filter.
 9. A filter wheel assembly comprising: a filter wheel comprising a main body bounding a plurality of viewing openings extending therethrough; a first optical assembly removably secured to the filter wheel, the first optical assembly comprising: a housing bounding an aperture extending therethrough; and an optical element secured to the housing so as to be positioned within or aligned with the aperture, the first optical assembly being removably secured to the filter wheel at a first one of the viewing openings by a first magnetic force between the first optical assembly and the filter wheel; and a first coupling portion and a second coupling portion respectively positioned on the filter wheel and the first housing, the first and second coupling portions being coupled with each other when the first optical assembly is secured to the filter wheel so as to align the aperture of the first optical assembly with the first viewing opening.
 10. The filter wheel assembly recited in claim 9, wherein the first and second coupling portions comprise a mating tenon and mortise.
 11. The filter wheel assembly recited in claim 10, wherein: the tenon comprises a pin positioned on the main body or the first housing; and the mortise forms a hole on the other of the main body or the first housing, the hole being configured to receive the pin.
 12. The filter wheel assembly recited in claim 11, wherein the mortise extends completely through the main body or the first housing.
 13. The filter wheel assembly recited in claim 9, further comprising a second optical assembly removably secured to the filter wheel at a second one of the viewing openings by a second magnetic force between the second optical assembly and the filter wheel.
 14. The filter wheel assembly recited in claim 9, further comprising a second optical assembly removably secured to the first optical assembly by a second magnetic force between the first optical assembly and the second optical assembly.
 15. The filter wheel assembly recited in claim 14, wherein the second optical assembly comprises a second optical element that is aligned with the aperture of the first optical assembly.
 16. A filter wheel assembly kit comprising: a filter wheel comprising: a main body bounding a plurality of viewing openings extending therethrough; and a plurality of first coupling portions positioned on the main body, each being positioned adjacent a separate one of the viewing openings; and a plurality of optical assemblies, each comprising: a housing bounding an aperture extending therethrough; an optical element secured to the housing so as to be positioned within or aligned with the aperture, the optical assembly being removably securable to the filter wheel at any of the viewing openings by a magnetic force between the optical assembly and the filter wheel; and a second coupling portion positioned on the housing, the second coupling portion being configured to couple with one of the first coupling portions when the optical assembly is secured to the filter wheel at the viewing opening corresponding to the first coupling portion, the second coupling portion being positioned so as to align the aperture of the optical assembly with the viewing opening.
 17. The filter wheel assembly kit recited in claim 16, wherein the optical assemblies are interchangeable on the filter wheel.
 18. The filter wheel assembly kit recited in claim 16, wherein the optical assemblies are also removably securable to each other.
 19. The filter wheel assembly kit recited in claim 18, wherein each optical assembly further comprises a third coupling portion positioned on the housing, the third coupling portion being configured to couple with the second coupling portion of any of the other optical assemblies.
 20. The filter wheel assembly kit recited in claim 19, wherein for each optical assembly, the third optical coupling portion is positioned so that when coupled with the second coupling portion of any of the other optical assemblies, the apertures of the coupled optical assemblies are aligned. 